- Patients 18 years old or older with progressive ataxia and positive genetic test for SCA6 will be recruited. Those who take medications known to affect DAT binding, such as Ritalin, Cocaine, and Adderall will be excluded. Those taking SSRIs for depression will be asked to stop the medications for at least 24 hours before the DaTscanTM. All study patients will have the decision making capability to understand the study and requirements and consent for themselves.